Spanish translation, cross-cultural adaptation, and validation of the Questionnaire for Diabetes-Related Foot Disease (Q-DFD)

Figures & data

Table 1 Summary of adjustments with mean comparison scores for each item pair

Questionnaire and item	Translated version (Spanish)	Back translation	First version		Adjustment	Second version		Final Spanish version
			Comparability of language (mean score)	Comparability of language (mean score)		Similarity of interpretability (mean score)	Similarity of interpretability (mean score)
Q-DFD Question 1	¿Qué edad tiene y cuál es su código postal?	What is your age and area code?	3.13	2.53	What is your age and what is your postcode?	1.37	1.33	¿Cuál es su edad y cuál es su código postal?
Q-DFD Question 5c	¿Ha sentido dolor en sus glúteos o zona inferior cuando camina, en el último mes?	Have you felt any pain in your gluteus or lower area while walking in the last month?	3.20	2.47	Have you felt any pain in your gluteus or bottom area while walking in the last month?	2.53	2.23	¿Ha sentido dolor en sus nalgas o zona inferior cuando camina, en el último mes?
Q-DFD Question 8a	¿Le ha indicado su medico, podólogo, especialista u otro profesional de la salud (PS) que usted ha perdido parte o toda la sensibilidad de sus pies debido a su diabetes?	Have you indicated your podiatrist, specialist, or other health professional (HP) that you have lost some or all feeling in your feet because of your diabetes?	3.63	3.70	Have your Doctor, specialist, or other health professional (HP) indicated that you have lost some or all feeling in your feet because of your diabetes?	2.33	2.03	¿Le ha indicado su médico, podólogo, especialista u otro profesional de la salud (PS) que usted ha perdido parte o toda la sensibilidad de sus pies debido a su diabetes?
Q-DFD Question 12d	¿Tiene callos en los dedos de sus pies?	Do you have blisters on your toes?	4.10	3.90	Do you have corns on your toes?	2.67	2.57	¿Tiene callos en los dedos de sus pies?

Abbreviation: Q-DFD, Questionnaire for Diabetes-Related Foot Disease.

Table 2 Participant characteristics used to determine validity and reliability of the survey

	Sample
	A	B1	B2	B3	C
Total participants	36	40	18	22	41
Sex, n (%)
Male	13 (36.1)	21 (52.5)	9 (50)	12 (54.5)	16 (39)
Female	23 (63.9)	19 (47.5)	9 (50)	10 (45.5)	25 (61)
Age, years
Mean ± SD	61.4 ± 8.7	66.6 ± 9.6	68.3 ± 10.9	65.1 ± 7.8	64.2 ± 9.6
Range	48–85	46–87	48–87	46–75	50–89
Diabetes duration, years
Mean ± SD	8.7 ± 6.2	18.4 ± 10.1	19.3 ± 9	17.6 ± 10.8	9.4 ± 6.5
Range	1–23	0.58–38	6–33	0.58–38	0.5–23

Notes: Sample A was used to determine criterion validity, sample B was used to determine construct validity (B1 = total clinic-based sample, B2 = clinic-based sample with foot complications, B3 = clinic-based sample without foot complications), sample C was used to determine intra- and inter-rater reliability.

Abbreviation: SD, standard deviation.

Table 3 Summary of statistics used to determine criterion and construct validity

	Kappa	Sensitivity %	Specificity %	LR+	LR−
Samples A and B combined (any diagnosis of DRFD)	0.823	0.835	0.941	14.153	0.175
Samples A and B combined (all components of DRFD)
DN	0.728	0.839	0.889	7.559	0.181
PVD	0.776	0.688	0.923	8.935	0.338
Ulcer	0.856	0.846	0.969	27.290	0.159
Amputation	1.000	1.000	1.000
Deformitya
Sample A (any diagnosis of DRFD)	0.774	0.804	0.915	9.459	0.214
Sample A (all components of DRFD)
DN	0.550	0.750	0.800	3.750	0.313
PVD	0.750	0.667	0.900	6.670	0.370
Ulcer	0.654	0.500	0.971	17.241	0.515
Amputation	1.000	1.000	1.000
Deformity	0.615	0.893	0.667	2.682	0.160
Sample B1 (any diagnosis of DRFD)	0.880	0.870	0.970	29.000	0.134
Sample B1 (all components of DRFD)
DN	0.893	0.933	0.960	23.325	0.070
PVD	0.805	0.714	0.943	12.526	0.303
Ulcer	0.875	0.909	0.966	26.735	0.094
Amputation	1.000	1.000	1.000
Deformityb
Sample B2 (complications group, all components of DRFD)
DN	0.824	0.933	0.750	3.732	0.089
PVD	0.753	0.714	0.846	4.636	0.338
Ulcer	0.886	0.909	0.875	7.272	0.104
Amputation	1.000	1.000	1.000
Deformityb
Sample B3 (no complications group, all components of DRFD)
DN	No respondent reported	0.040	1.000		0.960
PVD	No respondent reported	1.000	1.000
Ulcer	No respondent reported
Amputation	No respondent reported
Deformityb

Notes: Sample A shows correlation between questionnaire and clinical evaluation, while sample B shows correlation between questionnaire and medical records (B1 = total clinic-based sample, B2 = clinic-based sample with foot complications, B3 = clinic-based sample without foot complications). Patients were classed as having “any diagnosis of DRFD” if they presented with either one of DN, PVD, ulcer, amputation, or deformity.

a Deformity for sample A and B combined could not be obtained because it was not commonly recorded in the medical records of patients in sample B;

b deformity was not recorded in the medical records of patients in sample B.

Abbreviations: DN, diabetic neuropathy; DRFD, diabetes-related foot disease; LR+, positive likelihood ratio; LR−, negative likelihood ratio; PVD, peripheral vascular disease.

Table 4 Prevalence of individual components of diabetes-related foot disease according to the Q-DFD

	Prevalence (%)
	DN	PVD	Ulcer	Amputation	Deformity
Sample A	44.4	16.7	2.8	2.8	75.0
Sample B1	37.5	12.5	27.5	5.0	60.0
Sample B2	77.8	27.8	55.6	11.1	55.6
Sample B3	4.5	0.0	4.5	0.0	63.6

Notes: Sample A was used to determine criterion validity, sample B was used to determine construct validity (B1 = total clinic-based sample, B2 = clinic-based sample with foot complications, B3 = clinic-based sample without foot complications). Abbreviations: DN, diabetic neuropathy; PVD, peripheral vascular disease; Q-DFD, Questionnaire for Diabetes-Related Foot Disease.